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1.
植物抗胁迫类转录因子研究进展   总被引:1,自引:0,他引:1  
转录因子在植物应答生物和非生物胁迫中起着重要作用.在胁迫环境下,植物中特定的转录因子与抗逆基因上游的顺式作用元件结合,从而特异性地调控该基因在植物体内的表达,提高植物对环境胁迫的适应能力.该文概述了植物抗胁迫相关的4类转录因子:MYB类转录因子、bZIP类转录因子、WRKY类转录因子和NAC类转录因子的结构特点、调控机制以及它们在植物耐逆基因工程中的研究进展.  相似文献   

2.
植物转基因沉默的原因及对策   总被引:3,自引:0,他引:3  
转基因植物中转基因沉默已成为植物基因工程的一大障碍,转基因沉默的原因是多方面的,可能是由于转录前外源基因和内源基因的结构特性、伴置效应以及宿主植物的遗传调控;也可能是因为转录时启动子、转录因子和终止子的作用;还可能是由于转录后的修饰作用、外源基因表达特异性和环境等因素。为了克服转基因植物中转基因沉默,可以采取下列对策:选择适宜的外源基因和调控元件、采用适当的转化方法、使用更加简便快捷的筛选策略等。  相似文献   

3.
RNA可以单独或者通过与其它蛋白因子的相互作用参与基因表达的调控。在转录前水平,RNA分子可以通过介导DNA的甲基化或异染色质的形成来调控基因表达;在转录水平,RNA分子通过直接与转录因子或RNA聚合酶相互作用来调控基因表达;在转录后水平,RNA利用由siRNA和microRNA介导的RNA干扰机制,通过降解目标mRNA或阻碍目标基因的翻译来沉默基因的表达。此外,mRNA还可以通过感知环境中代谢物的浓度,通过形成核糖开关(riboswitch)来调控基因的表达;反义RNA可以从复制、转录和翻译3个水平上调控基因的表达。  相似文献   

4.
CBL-CIPK信号系统在植物应答逆境胁迫中的作用与机制   总被引:4,自引:0,他引:4  
植物在长期适应中演化形成感知、传导和应答逆境胁迫的精细调控机制,CBL—CIPK信号系统是近年来兴起、植物特有的依赖于Ca2+信号参与逆境胁迫调控的信号网络.CBLs感知逆境Ca2+信号,结合Ca2+后与蛋白激酶CIPKs特异作用,激活的CBL—CIPK复合体通过翻译后磷酸化下游靶蛋白,或调节转录因子及胁迫应答基因,实现不同细胞水平、组织部位抗逆性的调控.该系统具有特异性、多样性和复杂性,同时存在不同信号途径的交叉作用.目前响应高盐、低K+和高pHCBL~CIPK信号途径研究取得重要进展,有望通过基因工程结合分子设计育种途径快速高效提高作物抗逆性.但仍有待于鉴定出更多的CBL—CIPK信号成分,特别是鉴定特殊生境植物的信号成分,并解析其在逆境胁迫响应中的功能.  相似文献   

5.
多胺广泛参与植物生长、发育等生理生化进程和植物逆境应答反应,精氨酸脱羧酶(ADC)是植物多胺生物合成途径中的关键酶.为研究桃树ADC基因的结构和逆境胁迫转录表达情况,试验利用同源序列法克隆桃树PpADC基因,对基因序列、编码蛋白结构等进行生物信息学分析,应用qRT-PCR检测基因PpADC在不同逆境胁迫过程中的转录表达量.结果表明,桃树PpADC基因含有一个2 178 bp的开放阅读框,编码725个氨基酸,基因序列中不含有内含子结构;该基因编码蛋白与白梨精氨酸脱羧酶相似值高达90.14%,系统进化树分析表明PpADC基因与白梨、苹果和湖北海棠等蔷薇科果树ADC基因亲缘关系较近;低温、脱水、盐和乙烯处理能不同程度上调PpADC基因的转录表达水平,表明该基因在桃树应答逆境胁迫过程中发挥重要作用.  相似文献   

6.
植物脱落酸不敏感蛋白3(abscisic acid-insensitive 3,ABI3)属于植物特有的B3蛋白家族,是脱落酸(ABA)信号转导过程中重要的调控因子之一,可与ABI5(abscisic acid-insensitive 5)共同作用,来诱导ABA响应基因的表达,从而调节种子休眠和萌发.其功能缺失突变体在种子萌发、幼苗生长以及气孔运动过程中都对ABA不敏感.除此之外,ABI3还在非生物胁迫方面发挥重要作用.文章综述了植物ABI3转录因子的结构特点、生物学功能等方面的最新研究进展,以期对ABI3转录因子的分子调控网络有一定了解,对作物遗传改良有新的思考.  相似文献   

7.
转录因子是通过转录水平或转录后水平上调控目的基因的表达来调控植物生长发育及生理代谢的.MYB (v-myb avian myeloblastosis viral oncogene homolog)转录因子是最大的植物转录因子家族成员之一,参与了细胞分化、细胞周期的调节,激素和环境因子应答,并对植物次生代谢以及叶片等器官形态建成具有重要的调节作用.文章对MYB的发现及其结构特征和功能研究进展进行综述,为进一步开展MYB基因的克隆、功能研究和利用提供参考.  相似文献   

8.
转录因子是通过转录水平或转录后水平上调控目的基因的表达来调控植物生长发育及生理代谢的.MYB(v-myb avian myeloblastosis viral oncogene homolog)转录因子是最大的植物转录因子家族成员之一,参与了细胞分化、细胞周期的调节,激素和环境因子应答,并对植物次生代谢以及叶片等器官形态建成具有重要的调节作用.文章对MYB的发现及其结构特征和功能研究进展进行综述,为进一步开展MYB基因的克隆、功能研究和利用提供参考.  相似文献   

9.
冷休克蛋白是从真细菌中发现的,它不仅作为RNA分子的伴侣蛋白,同时还与细菌的多个生理过程有着密切的联系,如:对低温的适应、细胞生长的控制、营养胁迫等.冷休克蛋白引起冷休克反应的分子调控发生在转录和翻译两个水平上.  相似文献   

10.
将拟南芥中转录因子基因NACl上游调控区1kb克隆到pRD420质粒,构建由NACl启动子驱动绿色荧光蛋白基因(GFP)表达的植物表达载体,并以此载体转化烟草,对阳性转基因植株研究表明,GFP在根部有较高水平的表达.进一步用生长素、生长素拮抗剂NPA和赤霉素处理,荧光强度的变化表明:该调控区受生长素作用的同时也受赤霉素诱导.初步说明NACl基因不仅是一个生长素反应基因,同时可能也是一个赤霉素反应基因.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

14.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

15.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

16.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

17.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

18.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

19.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

20.
The non-orthogonal localized molecular orbital(NOLMO)is the most localized representation of electronic degrees of freedom.As such,NOLMOs are thus potentially the most efficient for linear scaling calculations of electronic structures for large systems.However,direct ab initio calculations with NOLMO have not been fully implemented and widely used,partly because of the slow convergence issue in the optimization of NOLMO.We devel-  相似文献   

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